You do not need a brilliant idea. You need one specific thing you can do well, that somebody near you already wants, and a reason they would pick you.
Most people arrive with too many ideas or none. Both are normal. This is work, not a failure.
The best idea is usually already in your life. Answer these on paper, honestly:
That last question matters as much as the others. A man who is losing his hearing and has only weekends has a different right answer than someone free every afternoon. Your limits are not in the way of the idea — they help you find the right one.
"I do handy work" is not an idea. "I assemble IKEA furniture" is.
Specific wins for three reasons. You get good at it faster. The customer knows immediately whether they need you. And you can be the best one at a small thing long before you could be good at a big one.
Take whatever you wrote and cut it down until it names one job a person could ask you for by name.
Someone on the South Side already does what you are about to do. Why would a customer pick you?
"I work hard" and "good prices" are not answers — everyone says those. A real answer is concrete:
If you cannot name one, that is the single most important thing to work on, and it is worth more than any other work you could do this month.
If you have several, do not agonise. Ask which one somebody has already paid for, or come closest to paying for. Start there. You can change your mind later — you cannot learn anything from an idea you never tested.
Tell the coach what you have. If you are stuck, say so and answer its questions — it will help you get to your own answer, and it will only suggest options if you ask it to. What ends up in your plan is what you decided.